I hope everyone had a great 2022; here’s to a happy and productive new year for you. I had something come up recently that seems clear-cut on the surface, but I am finding out there is a little more to this issue of zone valve box (ZVB) placement. Where do they go in a Category 1 space (Critical Care Space)?

Let us start with the verbiage from the code book 2018 NFPA 99, section 5.1.4.6. for this discussion.

“5.1.4.6 Zone Valves.

“5.1.4.6.1 All station outlets/inlets shall be supplied through a zone valve, which shall be placed as follows:

“(1) It is installed so that a wall intervenes between the valve and the outlets/inlets that it controls.

“(2)* It is readily operable from a standing position.

“(3) It is installed where it is visible and accessible at all times.

“(4) It is not installed where it can be hidden from plain view, such as behind normally open or normally closed doors.

“(5) It is not installed in a room with the station outlets/inlets that it controls.

“(6) It is not installed in rooms, areas, or closets that can be closed or locked.

“5.1.4.6.2 A zone valve in each medical gas or vacuum line shall be provided for each Category 1 space and anesthetizing location for moderate sedation, deep sedation, or general anesthesia specific for the occupancy. These zone valves shall be located as follows: (emphasis added)

“(1) They are installed immediately outside the area controlled.” (emphasis added) 

Note: Which should it be, area or space? Is area referring to the room/space or is it the department/unit?

“(2) They are readily accessible in an emergency.

“5.1.9.4.4 Alarm sensors for area alarms shall be located as follows:

“(1)* Category 1 spaces shall have the alarm sensors installed on the patient or use side of each individual zone valve box assemblies. (emphasis added)

“(2)* Category 1 space

“A.5.1.9.4(2) Examples of Category 1 space include post-anesthesia recovery, intensive care units, and emergency departments.” (emphasis added)

Note: Here, it talks as if the department/unit is a space. This example could be revised to say: “A Category 1 space includes post-anesthesia recovery (preop/PACU), Category 1 Patient Rooms that are within a Category 1 Area, and emergency departments.”

“3.3.134 Patient Bed Location. The location of a patient sleeping bed, or the bed or procedure table of a Category 1 space. (ELS) (emphasis added)

“3.3.136* Patient Care Space. Any space of a health care facility wherein patients are intended to be examined or treated. (FUN) (emphasis added)

“3.3.136.1* Category 1 Space. Space in which failure of equipment or a system is likely to cause major injury or death of patients, staff, or visitors. (FUN) (emphasis added)

“3.3.167 Space. A portion of the health care facility designated by the health care facility’s governing body that serves a specific purpose. (emphasis added)

“A.3.3.136.1 Category 1 Space. These spaces, formerly known as critical care rooms, are typically where patients are intended to be subjected to invasive procedures and connected to line-operated, patient care–related appliances. Examples include, but are not limited to, special care patient rooms used for critical care, intensive care, and special care treatment rooms such as angiography laboratories, cardiac catheterization laboratories, delivery rooms, operating rooms, post-anesthesia care units, trauma rooms, and other similar rooms.” (emphasis added)

Note: This states the critical care patient room is to be considered a Category 1 space.

After looking over the code book and how the language is written, it could be interpreted as the Category 1 Space (Critical Care Patient Room) will need its own ZVB, which was not the intent, but could be taken this way. One could gather from the code book that the ZVB should be outside each room by 5.1.4.6.2: “shall be provided for each Category 1 space.” 

I know if 5.1.4.6.2 (1) was written as “outside the room controlled,” it would definitely mean outside each patient room, but area (as it is written) says to me the department/unit where all the rooms are located.

We can all agree the box should not be required outside each Category 1 (Critical Care Patient) room, so how are we to follow the breadcrumbs and locate the zone valve box to be installed?

Inside or Outside?

Let’s look at the make-believe pediatric intensive care unit (PICU) floor plan in Figure 1 and work through the code to locate the ZVB. We know the space in question is a PICU inside a medical/surgical (Med Surg) wing.

Critical Care/Intensive Care Unit

Category 1 space (A.3.3.136.1)

Emergency exit route through Med Surg wing

Patient Care room has walls and doors (not glass doors)

Since the PICU patient room is considered a Category 1 space, then by code section 5.1.4.6.2 (1), the Category 1 space is inside the area controlled. How I believe the box is to be located is not inside the Category 1 space (room) but outside the area controlled, which would be inside the Med Surg part of the wing (outside the PICU unit). 

We can all agree a ZVB should not be installed outside each Category 1 patient room but outside the area served. Now, when we locate the ZVB inside the Med Surg wing, we need to locate it as close to the double doors leading into the critical care area to remove the confusion of which zone valve to close in an emergency. The Med Surg ZVB should be located near the double doors leading into the Med Surg wing, close to the nurse’s station. 

Many designers will decide to locate the ZVB for a critical care unit inside the area. In the event of an emergency, the fire department will enter from the double doors, through the Med Surg wing to access the ZVB from outside the area served. With the zone valve box inside the area served, the firefighters will likely enter the unit by the stairs, but will need to fight through a possible fire to get to the zone valve.

As you can see, it is not as clear-cut as one would think. Designers will need to determine many decisions on their own until the code can explain concisely where to locate the ZVB. Until then, make your best judgment call and coordinate with your local medical gas inspectors and verifiers to help determine where they would prefer the ZVB to be located.